The Through Wall Pass-Thru is a critical part of the product transfers which occur in every cleanroom. Although simple in design, the use of a Pass-Thru is essential to the maintenance of the high level of cleanliness within the cleanroom. The Pass-Thru significantly limits the amount of outside air exposed to the clean zone. With the use of either a mechanical or electrical interlock system, the cleanroom is protected from the cross-contamination which would occur if both doors were to open simultaneously. Atmos-Tech constructs Pass-Thrus for small or large parts, wheeled carts, and even personnel.